1. Field of the Invention
This invention relates generally to a system and method for determining an optimal vehicle path and, more particularly, to a system and method for determining an optimal vehicle path for the proper amount of braking and steering during a vehicle collision avoidance maneuver, where the optimal braking is determined by vehicle speed and road surface coefficient of friction using a two-dimensional table generated off-line and the optimal steering is determined based on the optimal braking and a friction ellipse.
2. Discussion of the Related Art
Collision avoidance systems and/or adaptive cruise control systems are known in the art that provide automatic vehicle control, such as braking, if a potential or imminent collision with another vehicle or object is detected, and also may provide a warning to allow the driver to take corrective measures to prevent the collision. For example, adaptive cruise control systems are known that employ a forward looking sensor, such as a radar or lidar sensor, that provides automatic speed control and/or braking if the vehicle is approaching another vehicle. Also, collision avoidance systems are known that employ sensors for determining if a collision with an object may be imminent that may provide vehicle braking even if the vehicle operator is controlling the vehicle.
These types of systems typically employ long-range sensors that have a narrow field-of-view in the near-field of the vehicle. Particularly, the sensor signals emanate from a point source on the vehicle and extend in the forward direction of the vehicle, typically to about 150 meters. The collision warning system transmits a radar or laser beam forward of the vehicle and process reflections from objects in the path of the vehicle. The system generates measurements from the reflections and assesses the potential for a collision based on the vehicle's speed, direction relative to the objects, road surface conditions, etc. The alert can be a visual indication on the vehicles instrument panel or in a head-up display (HUD), and/or can be an audio warning or other haptic feedback device, such as seat shaking.
Heretofore, collision avoidance systems have typically been limited to systems that provide automatic braking in the event that the vehicle driver does not take evasive action in time to prevent a collision. However, collision avoidance systems of this type may benefit from providing combined braking and steering to avoid a collision.